What is the Mucous Plug?

In order to prevent bacteria from entering the uterus and harming a fetus, women who are pregnant develop a mass of protective mucous in the cervical canal, commonly known as the mucous plug. The plug is one of the many natural steps that the human body takes to protect a growing fetus, and is an integral part of warding off bacterial infection of the uterus during pregnancy. Most women will lose their mucous plug as they near the end of pregnancy, but although passing the plug is a preliminary to labor, it does not necessarily indicate that labor is occurring. According to some experts, loss of the mucous plug becomes likely around the 36th week of pregnancy, even if birth does not occur for several additional weeks.

The plug can have a varied appearance, and some health care experts suggest it can not only differ from one woman to the next, but from pregnancy to pregnancy for an individual woman. Sometimes the plug is clear, although the presence of blood is quite common and may color the plug red, pink, or brown. While some women lose the plug all at once, others may experience a slow dissipation of the mucous plug that may easily be confused with normal discharge.

As the body approaches labor, the cervical tissue begins to thin and stretch in preparation for birth, a condition also known as “ripening.” It is during this time that the mucous plug will dislodge from its place at the cervical entrance, as the tissue is no longer thick enough to hold it in place. Ripening can take several weeks before labor occurs, leading to some confusion about whether losing the plug is a sign of labor. Some experts suggest that while loss of the plug is one of the first signs of approaching labor, it is by no means a sign that labor is occurring.

Doctors and experts also caution pregnant women to inform their doctor if there is abnormal vaginal bleeding before the plug is lost and labor approaches. Although blood is common in the mucous plug, vaginal bleeding can be a sign of serious medical conditions that can affect the health of both mother and child. Losing the mucous plug is not cause for panic, according to experts, but if blood or abnormal discharge occurs in the second or early third trimester, a health care provider should be notified.

Although the plug protects the uterus from infection during much of the pregnancy, losing the plug does not necessarily indicate a higher risk of bacterial infection. The amniotic sac that encloses the fetus will remain sealed until labor begins in earnest, and provides the baby with considerable protection against harmful bacteria. Many experts agree that the loss of the mucous plug is not cause for concern or panic, but rather an exciting indication that birth will occur within a few weeks.